The present disclosure relates to a method for damping torsional vibrations in a power generation plant, to a computing unit for carrying out the same and to a corresponding power generation plant.
Although, within the scope of this application, the present disclosure will primarily be described with reference to wind power plants, it is not restricted thereto but in principle can be used in all types of power stations and plants in which torsional vibrations of shafts, axles and the like, in particular also of shafts and axles with interposed gearboxes, can occur.
Drive trains, comprising components such as, for example, gearboxes, clutches and connecting elements (shafts), are important constituent parts of various electrical power generation plants, such as, for example, wind power plants, water power plants, etc. The drive train fulfills the task of producing a mechanical connection between a drive (for example a rotor of a wind power plant) and an output (for example an appropriate generator), via which energy is transmitted through a rotational movement. Drive train components, such as gearboxes, are used to transfer the rotational speed and the torque present on the drive to values which correspond to the working range of the generator. Clutches are used as required for isolation between drive and output, and shafts produce the mechanical connection between the components involved. In addition, further components, such as mechanical brakes or the like, can be integrated in the drive train.
Since the components involved cannot be made arbitrarily rigid but have a finite stiffness, excitations can lead to high dynamic loads and vibrations. In particular, natural vibrations can be excited. Such an excitation can result, for example, from a non-constant input power (in the case of wind power plants, for example as a result of wind gusts or wind turbulence), from external interference or from natural movements of other plant components. In addition, vibrations of another origin can result in vibrations in the drive train; in the case of a wind power plant, for example tower vibrations or vibrations on account of the tooth engagements of a gearbox.
Vibrations have a detrimental effect on the service life of the components involved, in particular of the gearbox. Continuous threshold loadings increase the wear of the components affected and lead to shorter replacement intervals, which means a financial and technical burden on the plant and network operator and reduces the plant revenue. In particular from the point of view of the anticipated increasing propagation of wind power plants in the offshore sector in the foreseeable future, this aspect plays a greater and greater role, since the replacement of damaged components is made more difficult there. The result is, therefore, the object of detecting these dynamic excitations and in particular of reducing the vibrations, in order to increase the service life of the components.
WO 2011/072820 A2 discloses a method for damping torsional vibrations in a power generation plant having a drive train, a rotor fitted to a rotor-side end of the drive train and a generator driven via the drive train and fitted to a generator-side end of the drive train, wherein, by using an angular position of the drive train at the generator-side end thereof and an angular position of the drive train at the rotor-side end thereof, a torsional moment acting on the drive train is determined, wherein torsional vibrations are damped by means of appropriate control of the generator.
This method is to be improved further. In particular, control concepts which lead to adequate damping of the torsional vibrations are desirable. It would also be advantageous to have available appropriate sensors (in particular those that are economical and suitable for mass production) which, in particular, are also suitable for updating existing drive trains.